Mr. Trump does look a lot like a real outsider candidate — and his surprising continued strength is obviously the biggest sign of a larger anti-establishment sentiment that could mark 2016 as different from previous cycles.

On the other hand, he is such a distinctive candidate — a genuine celebrity with a larger-than-life personality and the ability to draw tremendous media attention — that it’s not at all obvious that his support augurs anything more than support for Mr. Trump himself. His supporters are demographically and politically diverse, making it harder to infer what’s driving his support.

For anyone trying to figure out whether Republicans have entered a new pro-outsider phase, the roughly 25 percent who now say they’re supporting Mr. Trump will be more important to watch than the Fiorina and Carson supporters.

And what about the polling that suggests a majority of Republican voters might prefer a candidate who isn’t a Washington politician?